From 330e3a29c76e7582ae2169b6ed8cf6ae362431e6 Mon Sep 17 00:00:00 2001
From: core <core@coredoes.dev>
Date: Tue, 28 Nov 2023 18:05:56 -0500
Subject: [PATCH] API work

---
 starkingdoms-api/cmd/starkingdoms-api/main.go | 124 +++++++++++++++++-
 starkingdoms-api/config.go                    |   5 +
 starkingdoms-api/discord.go                   |  10 ++
 3 files changed, 137 insertions(+), 2 deletions(-)
 create mode 100644 starkingdoms-api/discord.go

diff --git a/starkingdoms-api/cmd/starkingdoms-api/main.go b/starkingdoms-api/cmd/starkingdoms-api/main.go
index 2d0a63d53de6d66b3e00b86823b57f76baf3b5bf..04d1f6527860202e77253c8a958dec4a4ee00706 100644
--- a/starkingdoms-api/cmd/starkingdoms-api/main.go
+++ b/starkingdoms-api/cmd/starkingdoms-api/main.go
@@ -4,11 +4,25 @@ import (
 	"flag"
 	"fmt"
 	"github.com/sirupsen/logrus"
-	starkingdoms_api "gitlab.com/starkingdoms.tk/starkingdoms.tk/starkingdoms-api"
+	starkingdomsapi "gitlab.com/starkingdoms.tk/starkingdoms.tk/starkingdoms-api"
+	"io"
+	"math/rand"
 	"net/http"
+	"net/url"
 	"os"
+	"strings"
 )
 
+var letters = []rune("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ")
+
+func randSeq(n int) string {
+	b := make([]rune, n)
+	for i := range b {
+		b[i] = letters[rand.Intn(len(letters))]
+	}
+	return string(b)
+}
+
 func main() {
 	configPath := flag.String("config", "config.yml", "File to load configuration file from")
 	printUsage := flag.Bool("help", false, "Show command line usage")
@@ -20,7 +34,7 @@ func main() {
 		os.Exit(0)
 	}
 
-	c, err := starkingdoms_api.LoadConfig(*configPath)
+	c, err := starkingdomsapi.LoadConfig(*configPath)
 
 	if err != nil {
 		fmt.Printf("failed to load config: %s", err)
@@ -45,7 +59,113 @@ func main() {
 		_, err := fmt.Fprintf(w, "pong")
 		if err != nil {
 			logrus.Error(err)
+			return
+		}
+	})
+
+	var stateMap = make(map[string]string)
+
+	http.HandleFunc("/discord/start", func(w http.ResponseWriter, r *http.Request) {
+		logrus.WithFields(logrus.Fields{
+			"remote": r.RemoteAddr,
+		}).Info("GET /discord/start")
+
+		redirectUri := r.URL.Query().Get("back")
+		if redirectUri == "" {
+			_, err := fmt.Fprintf(w, "Missing `back` parameter.")
+			if err != nil {
+				logrus.Error(err)
+				return
+			}
+			return
+		}
+
+		state := randSeq(20)
+		stateMap[state] = redirectUri
+		discordUrl := starkingdomsapi.DiscordApiUrl(c, state)
+		http.Redirect(w, r, discordUrl, http.StatusFound)
+	})
+
+	http.HandleFunc("/discord/callback", func(w http.ResponseWriter, r *http.Request) {
+		logrus.WithFields(logrus.Fields{
+			"remote": r.RemoteAddr,
+		}).Info("GET /discord/callback")
+
+		code := r.URL.Query().Get("code")
+		if code == "" {
+			_, err := fmt.Fprintf(w, "Missing `code` parameter.")
+			if err != nil {
+				logrus.Error(err)
+				return
+			}
+			return
+		}
+
+		state := r.URL.Query().Get("state")
+		if state == "" {
+			_, err := fmt.Fprintf(w, "Missing `state` parameter.")
+			if err != nil {
+				logrus.Error(err)
+				return
+			}
+			return
+		}
+
+		_, ok := stateMap[state]
+		if !ok {
+			_, err := fmt.Fprintf(w, "Invalid `state` parameter, cannot redirect back. Perhaps your login expired? Try starting over from the main login page.")
+			if err != nil {
+				logrus.Error(err)
+				return
+			}
+		}
+
+		delete(stateMap, state)
+
+		client := &http.Client{}
+
+		v := url.Values{
+			"grant_type":   {"authorization_code"},
+			"code":         {code},
+			"redirect_uri": {c.Discord.RedirectURI},
+		}
+
+		logrus.WithFields(logrus.Fields{
+			"sendingBody": v.Encode(),
+		}).Info("sending token request")
+
+		req, err := http.NewRequest("POST", "https://discord.com/api/v10/oauth2/token", strings.NewReader(v.Encode()))
+
+		if err != nil {
+			logrus.Error(err)
+			return
 		}
+
+		req.Header.Set("Accept", "application/json")
+		req.SetBasicAuth(c.Discord.ClientID, c.Discord.ClientSecret)
+
+		resp, err := client.Do(req)
+		defer func(Body io.ReadCloser) {
+			err := Body.Close()
+			if err != nil {
+				logrus.Error(err)
+				return
+			}
+		}(resp.Body)
+
+		if err != nil {
+			logrus.Error(err)
+			return
+		}
+
+		b, err := io.ReadAll(resp.Body)
+		if err != nil {
+			logrus.Fatal(err)
+		}
+
+		logrus.WithFields(logrus.Fields{
+			"resp": string(b),
+		}).Info("got authentication token")
 	})
 
 	logrus.Error(http.ListenAndServe(c.Server.Host+":"+c.Server.Port, nil))
diff --git a/starkingdoms-api/config.go b/starkingdoms-api/config.go
index fee169fb5d9eca4fa7a24a39be58b539b4e6f277..3db191b89b4617ec991e34c619074c80c721b093 100644
--- a/starkingdoms-api/config.go
+++ b/starkingdoms-api/config.go
@@ -15,6 +15,11 @@ type Config struct {
 		Format string       `yaml:"format"`
 		Level  logrus.Level `yaml:"level"`
 	} `yaml:"logging"`
+	Discord struct {
+		ClientID     string `yaml:"client_id"`
+		ClientSecret string `yaml:"client_secret"`
+		RedirectURI  string `yaml:"redirect_uri"`
+	} `yaml:"discord"`
 }
 
 func LoadConfig(path string) (*Config, error) {
diff --git a/starkingdoms-api/discord.go b/starkingdoms-api/discord.go
new file mode 100644
index 0000000000000000000000000000000000000000..ca9df3f83379a4985793db9dc1525a76dcf0d111
--- /dev/null
+++ b/starkingdoms-api/discord.go
@@ -0,0 +1,10 @@
+package starkingdoms_api
+
+import (
+	"fmt"
+	"net/url"
+)
+
+func DiscordApiUrl(c *Config, state string) string {
+	return fmt.Sprintf("https://discord.com/api/oauth2/authorize?client_id=%s&redirect_uri=%s&response_type=code&scope=identify&state=%s", c.Discord.ClientID, url.QueryEscape(c.Discord.RedirectURI), state)
+}